Floating-ring shaft seal

ABSTRACT

A shaft seal for sealing off an opening where the shaft passes through a wall enclosing a pressurized space comprises a floating sealing ring located within a recess in the wall opening and surrounding the shaft. A fluid sealing medium is introduced into the recess under pressure which causes the sealing ring to be forced axially in the direction of a wall surface within the recess, and a supporting member, for example, in the form of an assembly of axially extending rods surrounds the shaft intermediate the sealing ring and the wall surface to take up the force applied against the sealing ring by the pressurized sealing medium. The axially extending rods are stiff in an axial direction but flexible in a radial direction so as to allow the ends thereof in contact with the sealing ring to shift radially and accommodate themselves to radial shifts of the sealing ring. A cylindrical liner can be installed around the rod assembly to seal it off from pressures which would otherwise be exerted directly against it by the pressurized sealing medium.

United States Patent [72] Inventors Hans Baumann Hombergsteig 15,Nussbaumen; Heinrich Lorenzen, Auguartenstrasse 221, Ennetturgi,Switzerland [21] Appl. No. 791,449

[22] Filed Jan. 15, 1969 [45] Patented Feb. 9, 1971 [32] Priority Jan.25, 1968 [3 3] Switzerland [54] F LOATING-RING SHAFT SEAL 4 Claims, 4Drawing Figs.

3,149,846 9/1964 Verbeek 277/71X Primary ExaminerFrederick L. MattesonAssistant Examiner-Harry B. Ramey Attorney-Pierce, Scheffler and ParkerABSTRACT: A shaft seal for sealing off an opening where the shaft passesthrough a wall enclosing a pressurized space comprises a floatingsealing ring located within a recess in the wall opening and surroundingthe shaft. A fluid sealing medium is introduced into the recess underpressure which causes the sealing ring to be forced axially in thedirection of a wall surface within the recess, and a supporting member,for example, in the form of an assembly of axially extending rodssurrounds the shaft intermediate the sealing ring and the wall surfaceto take up the force applied against the sealing ring by the pressurizedsealing medium. The axially extending rods are stiff in an axialdirection but flexible in a radial direction so as to allow the endsthereof in contact with the sealing ring to shift radially andaccommodate themselves to radial shifts of the sealing ring. Acylindrical liner can be installed around the rod assembly to seal itoff from pressures which would otherwise be exerted directly against itby the pressurized sealing medi- FLOATING-RING sum SEAL The inventionrelates to a floating-ring seal for sealing off the place where a shaftpasses through the wall of a pressurized space filled with gas orliquid, the foating-ring being axially pressed with great force againstthe wall under the action of a sealing medium, and being radiallymoveable for the purpose of adaption to shaft movements.

Floating-ring seals for sealing off against high pressures in the mediumwhich is required to seal and involving correspondingly high sealingmedium pressures, are attended by the problem that the ring whichprovides a seal with respect to atmosphere is axially pressed with verygreat force against its supporting surface. The resultant frictionnecessitates a large radial displacement force for the floating-ringwhen the shaft moves or vibrates, and from a definite sealing mediumpressure upwards the said displacement force can no longer betransmitted by the film between the ring and the shaft. The consequenceis destruction of the film, and wear occurs on the ring and the shaft.At very high pressures, the strange situation arises that the shaft isguided as in a badly designed bearing in a floating ring which is nolonger fioating." If any unbalance occurs in the rotor, there is thedanger of the floating ring being destroyed, which not only makes theseal ineffective, but can lead to damage to the machine.

In order to avoid these disadvantages, it has already been proposed(German Pat. application A 53 I69 XII/47 f) to support the floating ringagainst the housing via an additional force-transmitting surface inorder to relieve the load on its sealing surface. However, it hastranspired that at high contact pressures either the sum of thefrictional resistances is still too high to keep the displacement forcewhich is necessary to overcome the said sum within permissible limits,or the Hertzian surface-pressure is too great. Hydraulic pressure relieffor the floating-ring is of assistance, but more expense is involved andthe consumption of sealing medium at high pressure increases.

The present invention'is based on the problem of avoiding thedisadvantages and dangers indicated even at the very high axial forcesat which the floating ring is pressed against the wall, and of ensuringthat the floating ring is easily displaceable in the radial direction.According to the invention, this problem is solved by a supportingmember which extends axially between the wall and the floating ring,which transmits the contact force and is axially stiff, and whereof theend which comes to bear against the floating ring is radiallydisplaceable with respect to the end pressed against the wall.

In the accompanying drawings, an overall arrangement of afloating-ring-type seal to which the present invention relates, isillustrated in section in FIG. 1;

FIG. 2 is a view in axial section illustrating such a shaft seal inaccordance with one embodiment of the invention;

FIG. 3 is also an axial section illustrating a shaft seal in accordancewith a second embodiment of the invention; and

FIG. 4 is view in perspective of a supporting member for thefloating-ring seal according to a third embodiment of the invention.

With reference now to the drawings, at the place where the shaft 1passes through the wall 2, floating rings 3, 4 are accommodated inrecesses 20, and have the task of preventing a gas or liquid fromflowing out along the shaft from the highly pressurized space 5 to thesurrounding atmosphere 6. A sealing medium which may be gaseous orliquid and is at higher pressure than the medium to be sealed is fedthrough the pipe 7. The sealing medium forces the floating ring 3 withgreat force axially, in the drawing to the left, against the wall. Inorder to keep the floating ring radially movable in spite of the highcontact pressure, a supporting member 8 within the recess extendsbetween it and the wall. This member must be capable of transmittingaxial forces, but of allowing for radial movements on the part of thefloating ring 3.

Possibilities for embodying the supporting member are de picted in thefollowing FIGS. According to FIG. 2, it consists of cylindrical arrayrods 9 axially parallel to the shaft 1 which are axially stiff anduniformly distributed over the circumference. In order to facilitateassembly, and also if appropriate to increase resistance to bending,they may expediently be linked to one another, but this must not impairtheir flexibility. They are loosely inserted by way of their ends intothe wall and into the floating ring, and cemented, welded, soldered orotherwise fastened to these parts.

If one end of the rods is held fast in the manner described in the wall,the other ends thereof and together with them the floating ring cancarry out a radial movement without any large force being necessary forthat purpose. On the other hand, the rods are capable of transmitting alarge axial force from the floating ring to the wall. In order toprevent the sealing medium from flowing away freely between the rods,the wall includes a shoulder 10 in conjunction with which the floatingring forms a narrow sealing gap, whereof the width may be set by theaxial size of the supporting member, the rods in the example accordingto FIG. 2.

According to FIG. 3, the supporting member is provided with annular endplates 11,12, to which the force-transmitting rods 9 are fastened in oneof the ways mentioned. The end plate 11 bears against the wall 2, andthe end plate 12 bears against the floating ring 3, which is thusradially movable.

A possible method of blocking-means sealing, namely the arrangement ofan additional sealing gap between the floating ring and the wall, wasshown in the case of the embodiment according to FIG. 2. Anotherpossibility is indicated in FIG. 3. Between the end plates 11, 12 thereis a liner element 13, which may be an elastic jacket of any kind, forexample, a stiffened or sufficiently stiff bellows, arranged outside orinside the rods, or even an annular filler linking the rods may be used.The essential thing is that the liner 13 of the supporting member shallconstitute a seal with respect to scaling medium and pressure, and shallnot hinder radially movements on the part of the floating ring.

Tubes of correspondingly small diameter may also be used instead of therods 9. FIG. 4 shows another design for the supporting member. Itconsists of a single tube 14 surrounding the shaft. The tube is providedwith longitudinal slits 15 in such a manner that rodlike fillets remain,resulting in the same action as in the case of individual rods or tubes.A supporting member formed in this manner may also be provided with endplates.

The use of a supporting member between the wall and the floating ring,which member can transmit even the greatest axially acting forcesencountered and which is supported by way of one end against the wall,while the other end, which can yield to bending forces, is supportedagainst the floating ring, results in the latter being radially movableand being able to fulfill unhindered its task as a sealing element forthe place where a shaft passes through a wall.

We claim:

1. In a floating-ring-type shaft seal for sealing off floating ringopening where the shaft passes through a wall enclosing a pressurizedspace filled with gas or liquid, the combination comprising a floatingsealing ring located within a recess in the wall opening and whichsurrounds said shaft, means for introducing a fluid sealing medium intosaid recess under pressure, the pressure of said sealing medium beingexerted against one end face of said sealing ring, and supporting meanslocated within said recess and interposed between the other end face ofsaid sealing ring and said wall for transmitting the fluid pressureexerted by said sealing medium against said floating ring to said wall,said supporting means being constituted by a cylindrical array ofcircumferentially spaced rodlike axially stiff but radially movablemembers surrounding said shaft and axially parallel therewith, saidrodlike supporting member having one end thereof bearing against saidwall and the other end bearing against said sealing ring.

2. A shaft seal of the floating-ring-type as defined in claim 1 andwhich further includes a liner surrounding said supporting means withinsaid recess, said liner serving to seal off said supporting means fromthe pressure of said fluid sealing medium.

established by an axially stiff tubular member surrounding said shaftand axially parallel therewith, said tubular member being provided withcircumferentially spaced axially extending slits which thereby developrodlike fillets therewith.

Patent No. 3,5 ,773 Dated February 9, 1971 Inventor s HANS BAUMANN andHEINRICH LORENZEN It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Claim 1, lines 1 and 2, cancel "floating ring" and substitute an Signedandsealed this 18th day or May 1 971 (SEAL) Attest: I

EDWARD M.FLETCHER,JR. WILLIAM SCHUYLER, Attes'ting Officer Commissionerof Pate

1. In a floating-ring-type shaft seal for sealing off floating ringopening where the shaft passes through a wall enclosing a pressurizedspace filled with gas or liquid, the combination comprising a floatingsealing ring located within a recess in the wall opening and whichsurrounds said shaft, means for introducing a fluid sealing medium intosaid recess under pressure, the pressure of said sealing medium beingexerted against one end face of said sealing ring, and supporting meanslocated within said recess and interposed between the other end face ofsaid sealing ring and said wall for transmitting the fluid pressureexerted by said sealing medium against said floating ring to said wall,said supporting means being constituted by a cylindrical array ofcircumferentially spaced rodlike axially stiff but radially movablemembers surrounding said shaft and axially parallel therewith, saidrodlike supporting member having one end thereof bearing against saidwall and the other end bearing against said sealing ring.
 2. A shaftseal of the floating-ring-type as defined in claim 1 and which furtherincludes a liner surrounding said supporting means within said recess,said liner serving to seal off said supporting means from the pressureof said fluid sealing medium.
 3. A shaft seal of the floating-ring-typeas defined in claim 1 and which further includes annular end plateslocated at the opposite ends of said cylindrical array of rodlikemembers and secured thereto.
 4. A shaft seal of the floating-ring-typeas defined in claim 1 and wherein said cylindrical array of rodlikemembers is established by an axially stiff tubular member surroundingsaid shaft and axially parallel therewith, said tubular member beingprovided with circumferentially spaced axially extending slits whichthereby develop rodlike fillets therewith.